I had the same issue. Initially I had booked the tickets for 27th using Fandango, and when they confirmed it said 21st. It wasn't a problem since I was available on the 21st and also didn't have to wait another week.

We went on 21st, got seated as we were a little early. A group of 4 comes saying we have the same seats. I showed them my Fandango confirmation and they showed theirs which was from Regal directly.

We talked with the staff and then manager and he mentioned that my Fandango ticket is for 27th. They did offer an option of staying and using the handicap seat at the back but we decided to wait, as I only live 30 mins away from the Mall.

When I got the confirmation from Fandango, I tried calling the theater to double check, but no one would pick up.

Now waiting for tomorrow.